Patent GB-1102342-A (GB)
Title: Improvements in or relating to the production of elongated binder particles of polymeric materials
Inventor: FAIRFULL ANDREW EWAN SPOWART
IPC: D21H13/34
Filed: 1963-07-22
Abstract: Elongated particles of polymeric materials are produced by a process comprising freezing an aqueous dispersion of the polymer and then thawing the frozen dispersion to obtain the particles, the concentration and stability of the dispersion prior to freezing being so selected that the polymer on thawing takes the form of particles substantially all of which have lengths substantially greater than their widths or depths and the lengths of the particles lie within the range between substantially 0.02 and 3.00 mm.  The particles generally have widths of from 0.0005 mm. to 0.4 mm. and depths of from 0.0005 mm. to 0.04 mm. Polymers specified are natural rubber and butadieneacrylonitrile, butadiene-styrene, or butadienemethacrylate rubbers, polyacrylates, polyvinyl chloride, polyvinylidene chloride and vinyl chloride-vinyl acetate copolymers.  The dispersion may be frozen in a thin-walled vessel, in contact with a cooled metal bar or by contacting the dispersion with a cooled travelling surface e.g. an endless metal belt.  A suitable apparatus (not shown) comprises a travelling surface, means for applying the dispersion to said surface, freezing means including the cooling coil of a compressor refrigeration apparatus, for freezing the dispersion while on the travelling surface and heating means including the condenser portion of the refrigeration apparatus for supplying heat to thaw the frozen dispersion (see Division F4).  The suspensions treated in the examples are (1) polyacrylate suspensions which are subsequently mixed with rayon flock and, in some cases, pentadecaethylene glycol nonyl phenol or a brown pigment, coniferous bleached sulphite pulp, eucalyptus wood pulp or mercerized wood pulp; (2) a suspension of natural rubber or of a butadiene-acrylo-nitrile, butadiene - methacrylate, butadiene-styrene or carboxy-butadiene-styrene rubber, which is subsequently mixed with rayon flock, an alkylated aryl polyether alcohol or bleached sulphite wood pulp; and (4) a polyvinylidene chloride suspension which is subsequently mixed with coniferous bleached sulphite pulp. The treated suspensions are used in the formation of films (see Division B5) and fibrous sheets (see Divisions D1 and D2) and for the coating of leather (see Divisions B2 and C6).ALSO:An aqueous suspension of polymer particles is drawn against a surface of a piece of leather by suction through the leather, and forms a coating on said surface.  The particles have specific dimensions (see Division C3) and partly penetrate the pores of the leather to increase its abrasion resistance.  In example 6 an aqueous suspension containing a polyacrylate and a brown pigment is applied to a surface of an unfinished leather upper. The resulting coated leather upper is then dried for 10 minutes at 140 DEG C.  The dried coating is well-keyed to the leather and imparts, to it, a pigmented, smooth finish.ALSO:A porous material is coated with a polymer by drawing an aqueous suspension of elongated polymeric binder particles, e.g. of natural or synthetic rubber such as butadiene-acrylonitrile, butadiene-methacrylate, polyacrylate, polyvinyl and polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, against the surface of said material by suction.  The polymer particles have specific dimensions (see Division C3).  In examples an aqueous suspension containing a polyacrylate and a brown pigment is applied to a leather upper and an aqueous suspension containing a polyacrylate and rayon flock, or polyvinylidene chloride alone, is applied to synthetic leather.ALSO:A fibrous web is formed by drawing a suspension containing elongated binder particles of a polymeric material and material or synthetic fibres against a porous surface.  The binder particles have specified dimensions and are formed by freezing and thawing an aqueous dispersion of the polymer (see Division C3). Specified fibres are those of cotton, wool, rayon, polyamides, polyesters and acrylics.  In the examples sheets are formed from a suspension containing rayon flock and a polyacrylate, a butadiene-acrylonitrile rubber, a butadiene-methacrylate rubber, a butadiene-styrene rubber, or natural rubber by pouring the suspension through a Buchner funnel and applying suction. Sheets are also formed, using a hard paper making apparatus, from a polyacrylate and coniferous bleached sulphate pulp, eucalyptus wood pulp or mercerised absorbent wood pulp, from polyvinylidene chloride and unbeaten bleached sulphite pulp, and from a carboxy-butadiene-styrene rubber and bleached sulphite wood pulp.